Step1: get path of ur dir.
Step2: check that path is dir or not .,
Step3: if its dir ., make recursion to that method and pass that path ., to the same method .,
step4: if its file add to arraylist ., its path else do the recursion .,
try to do code ., it ., if u have some problem then i will post my code ., u can have it as a sample